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## Main Question or Discussion Point

Hi,

I running a full CI calculation for low Z elements (up to Ne) in order to obtain the lowest lying electronic energy levels.

I can't seem to get correct results even though I'm using 1-electron states from first 4-6 electron shells. I am also using singly and doubly excited multi-electron states (wrt the ground state).

The errors I get in the ground state are around 5% of it's value ?

Is this error normal for a full CI like the one I described ?

If so how many 1-e states is it necessary to include to get the first excited energies correctly ?

Appreciate any help.

Thanks.

I running a full CI calculation for low Z elements (up to Ne) in order to obtain the lowest lying electronic energy levels.

I can't seem to get correct results even though I'm using 1-electron states from first 4-6 electron shells. I am also using singly and doubly excited multi-electron states (wrt the ground state).

The errors I get in the ground state are around 5% of it's value ?

Is this error normal for a full CI like the one I described ?

If so how many 1-e states is it necessary to include to get the first excited energies correctly ?

Appreciate any help.

Thanks.